Prior art devices for attaching/detaching snap rings are of two types: one being specialized for attaching/detaching a shaft snap ring into/from a groove of a shaft surface by extending an interval between both ends of the shaft snap ring; and the other being specialized for attaching/detaching a hole snap ring into/from a groove of a hole surface by narrowing an interval between both ends of the hole snap ring.
Specifically, in the device specialized for attaching/detaching a shaft snap ring, levers each of which is continuously formed in an approximately dogleg shape from a locking projection on a leading side to a grasp portion on a root side, are disposed to be symmetric with each other. The levers are connected to each other such that both the locking projections are parallel to each other, with the bent portions of the levers being rotatably supported. Both the locking projections are curved outward, that is, in the direction where they are separated from each other. In operation of the device, the locking projections are inserted in holes formed at both the ends of a snap ring and then moved apart from each other by tightening of grasp portions, so that an interval between both the ends of the snap ring is extended by the movement of the locking projections. At this time, since the locking projections are curved outward, the locking relationship between the holes of the snap ring and the locking projections is prevented from being released, thus certainly attaching/detaching the shaft snap ring into/from a groove of a shaft surface.
The device specialized for attaching/detaching a hole snap ring has a pair of right and left levers, each of which has a locking projection on the leading side and a grasp portion on the root side. The levers are crossed to each other in an X-shape, and they are connected to each other with the crossing portions being rotatably supported. Both the locking projections are curved inward, that is, in the direction where they come closer to each other. In operation of the device, the locking projections are inserted in holes of a snap ring and then moved nearer to each other by tightening of grasp portions, so that an interval between both the ends of the snap ring is narrowed by the movement of the locking projections. At this time, since the locking projections are curved inward, the locking relationship between the holes of the snap ring and the locking projections is prevented from being released, thus certainly attaching/detaching the hole snap ring into/from a groove of a hole surface.
These devices, however, have a disadvantage in that they cannot be commonly used for a shaft snap ring and a hole snap ring.
To cope with such a disadvantage, there has been proposed a device for attaching/detaching a shaft snap ring and a hole snap ring in U.S. Pat. No. 4,476,750 (see FIGS. 20 and 21).
This device can be switched between both types for hole and shaft applications by pushing right and left movable pins 100, 101 in the reversed direction. The device can be set up in the type operable around a supporting shaft 106 for shaft application by integrally connecting a right operating lever 102 to a right grasp lever 103 by means of the right movable pin 100, and a left operating lever 104 to a left grasp lever 105 by means of the left movable pin 101. On the other hand, the device can be set up in the type operable around the supporting shaft 106 for hole application by integrally connecting the left operating lever 104 to the right grasp lever 103 by means of the left movable pin 101, and the right operating lever 102 to the left grasp lever 105 by means of the right movable pin 100. In operation of the device, by tightening of the right and left grasp levers 103, 105, both locking projections 107, 108 provided at the leading edges of the right and left operating levers 102, 104 are moved apart from each other, or nearer to each other.
When a shaft snap ring is attached/detached, the right movable pin 100 is pushed up so as to be engaged with a pin hole 109 of the right operating lever 102 and a right engaging hole 110 of the right grasp lever 103, as a result of which the right operating lever 102 is integrally connected to the right grasp lever 103; whereas the left movable pin 101 is pushed down so as to be engaged with a pin hole 111 of the left operating lever 104 and a left engaging hole 112 of the left grasp lever 105, as a result of which the left operating lever 104 is integrally connected to the left grasp lever 105 (in the state shown by the virtual line in FIG. 21). In such a state, by tightening of the right and left grasp levers 103, 105, both the locking projections 107, 108 are moved apart from each other, so that an interval between both the ends of the snap ring is extended by the movement of both the locking projections 107, 108, thus attaching/detaching the snap ring into/from a groove of a shaft surface.
When a hole snap ring is attached/detached, the left movable pin 101 is pushed up so as to be engaged with a pin hole 111 of the left operating lever 104 and a left engaging hole 113 of the right grasp lever 103, as a result of which the left operating lever 104 is integrally connected to the right grasp lever 103; whereas the right movable pin 100 is pushed down so as to be engaged with a pin hole 109 of the right operating lever 102 and a right engaging hole 114 of the left grasp lever 105, as a result of which the right operating lever 102 is integrally connected with the left grasp lever 105 (in the state shown in FIG. 21). In such a state, by tightening of the right and left grasp levers 103, 105, both the locking projections 107, 108 are moved nearer to each other, so that an interval between both the ends of the snap ring is narrowed by the movement of both the locking projections 107, 108, thus attaching/detaching the snap ring into/from a groove of a hole surface. In this way, a shaft snap ring and a hole snap ring can be attached/detached using only one device.
In addition, as described above, for attaching/detaching a shaft snap ring, the right and left locking projections 107, 108 must be curved outward; whereas for attaching/detaching a hole snap ring, the right and left locking projections 107, 108 must be curved inward. If the directions of the locking projections 107, 108 are not suitably adjusted, there is a fear that the snap ring is slipped and jumped off the locking projections.
For this reason, in accordance with the kind of a snap ring (for shaft or hole application), the device is set up in the type for shaft or hole application by turning the right and left locking projections 107, 108 by 180.degree. around the axial line.
To switch the type of the device, three operations of the right and left locking projections 107, 108 must be performed: (1) loosening screws 115, 116 fixing the locking projections 107, 108; (2) turning the locking projections 107, 108 by 180.degree.; and (3) tightening the screws 115, 116 for fixing the locking projections 107, 108 again.
For switching the type of the device, there is further required an operation of pushing both the movable pins 100, 101. As a result, in the device proposed in U.S. Pat. No. 4,476,750, a shaft snap ring and a hole snap ring can be attached/detached by one device; however, the switching of the type of the device cannot be performed by one operation and takes a lot of labor.
Another problem presents in the directions of the locking projections 107, 108 upon insertion thereof. Upon insertion of the locking projections 107, 108, it must be confirmed whether the locking projections 107, 108 are both directed outward (for shaft application) or inward (for hole application). In this regard, this prior art device has a structure that even if one locking projection is directed outward and the other is directed inward, they are allowed to be inserted, which possibly causes an artificial trouble that the locking projections are inserted in the state that the directions thereof are erroneous. Moreover, if an operator does not know that the right and left locking projections must be adjusted in the state where they are both directed outward or inward, the same trouble is possibly generated.
In this case, as described above, if the directions of the locking projections 107, 108 are not suitably adjusted, there is a fear that the snap ring is slipped and jumped off the locking projections.